Our walling systems

There isn’t one right way to build.

Six systems

All of them produce a warm, quiet, well-made building. They differ in how far they take the performance, and what that costs.

Any of the six can be specified to reach passive house levels of thermal and airtightness performance, with greater wall depth and additional vapour control where the target requires it; in practice most passive house projects use twin wall, 4Wall or EI SIP. Working out which one suits your building, or whether a hybrid of two suits it better, is part of the first conversation.

The range

Six systems, one factory.

4Wall

Cement-bonded facings around a deep insulated core. Patented, Kiwa certified. The fabric behind The Walled Garden.

EI SIP

Timber-faced insulated panels, Kiwa certified, and the choice of most self-builders. The cost-effective route to low energy.

Open-panel timber frame

Arrives as a sheathed and squared frame, with the insulation fitted on site by our own team once it’s erected.

Filled-panel timber frame

Arrives with the insulation already cut in and the faces left open. The middle way between open and closed panel.

Closed-panel timber frame

Arrives complete and boarded, with the least left to do on site. The quickest of the three to a weathertight shell.

Twin-wall timber frame

Two structural leaves with a deep insulated cavity between them. For those targeting passive house and beyond.

Case studies

See how our buildings come together.

Brightlingsea School Extension

BRE Overview Full Version

Two SIP systems

Two patented SIP systems. Four timber frame systems. One factory.

4Wall is our most robust system: cement-bonded particle board facings around an insulated core, patented in the UK, Europe and the US. EI SIP uses timber-based facings around the same insulated core and is the system most self-builders choose; patent pending.

Both hold BDA Agrément certificates issued by Kiwa — BAW-20-175-S-A-UK for 4Wall, BAW-25-384-S-A-UK for EI SIP — covering structure, fire, moisture, thermal performance and durability. Standard U-values are 0.14 W/m²K for 4Wall and 0.13 W/m²K for EI SIP, each at 185 mm. The certificates are ours, for panels we make ourselves, not a supplier’s certificate for a product we buy in.

Alongside them, four timber frame systems — open, filled and closed panel, and twin wall — made on the same line and familiar to any builder.

Learn more from our brochure

Made here

One factory, at Butterleigh in mid Devon.

Everything structural is manufactured at Butterleigh — 4Wall, EI SIP, timber frame in open, filled and closed panel form, and twin wall — along with internal walls, cut to your drawings. Panels are manufactured to tolerance, checked, assembled flat and kept dry, so they arrive square and they fit.

Roof and floor structures, glulam and steel come from specialist suppliers; the wall systems are our own. The factory is audited regularly by the certification bodies whose marks appear below, and you’re welcome to visit.

Book a factory visit